1. Field of the Invention
The present invention relates to the management of stormwater runoff, and more particularly concerns devices which minimize and facilitate sediment maintenance, expand the storage capacity of stormwater management systems, and facilitate the infiltration of stormwater into the surrounding substrate.
2. Description of the Prior Art
Culverts, catch basins, and storm sewers are the common practices for collecting and conveying stormwater runoff. In some instances such water is discharged directly into the nearest available water body despite the potentially adverse environmental effects of such action. In some other instances, stormwater management facilities are constructed to help manage the quantity and quality of the stormwater. Wet or dry retention or detention basins/ponds represent the most common structural approach to stormwater management. Although more environmentally sound than direct discharge into an existing water body, such stormwater management approaches preclude other uses of the land. This is of particular importance where land values are high and/or space is limited. The open ponds may also be undesirable in locations near airports because of birds attracted by the pond, or in locations where health, liability or aesthetic considerations make them undesirable. Even the use of “dry” detention basins frequently results in the same types of problems associated with wet ponds. Without proper maintenance, dry detention basins frequently transform into wet ponds.
Underground systems have also been developed to help manage stormwater effluent. Such systems include the use of plastic arch-shaped, open bottom chambers arranged end-to-end in rows. However, all current underground stormwater management systems are limited by the amount of area available for their installation. This is particularly relevant to the plastic stormwater chambers. Although maximum size of the chamber is desirable, the strength of the chamber with respect to crushing by the overlying substrate generally diminishes with increased chamber size.
In a typical installation of plastic stormwater chambers, elongated hollow plastic chambers are emplaced in the ground to form a leaching field for receiving stormwater and dispensing the water into the surrounding earth. Such chambers have a central cavity for receiving inflow water. An open bottom, and apertures optionally located in the sides of the chambers provide the means whereby the water is allowed to exit the central cavity and disperse into the surrounding earth. The chambers are usually attached endwise to form long rows extending in side-by-side juxtaposition and seated upon a crushed rock substrate in a multi-row array that constitutes a leaching field. The stormwater is generally conducted to the array of rows by a large diameter header manifolded pipe system that runs orthogonally to the rows closely adjacent one extremity thereof.
Examples of stormwater dispensing chambers are disclosed in U.S. Pat. Nos. 5,017,041; 5,156,488; 5,336,017; 5,401,116; 5,441,363; 5,556,231 and 6,361,248.
Stormwater typically carries considerable amounts of suspended particulate material, commonly referred to as Total Suspended Solids (TSS), which eventually settles out as sediment within the stormwater management system. The accumulation of such sediment adversely affects the storage capacity of stormwater management facilities, decreasing their effective life. The effective life of such facilities can be significantly extended with a maintenance program for sediment removal. By virtue of the present invention, sediment removal can be achieved by a vacuuming operation conducted by a suitably equipped truck. In such operation, a tube is extended from the truck through a surface access structure, through an associated riser pipe, and into the bottom of the chamber. The sediment in the bottom of the chamber is then removed by vacuuming.
Unfortunately, the maintenance of stormwater management systems is typically neglected, causing sediment to accumulate to a point where flooding occurs because of diminished storage capacity of the system. This problem has become so serious that some municipalities have imposed a stormwater maintenance “fee” on property owners to help pay for private-sector stormwater facility maintenance.
Unlike stormwater wet and dry ponds, which are readily observable and accessible, removal of sediment from underground stormwater management facilities has historically been inherently more inconvenient and costly, resulting in resistance to their use by some municipalities. Some types of underground stormwater management facilities even have to be replaced in order to remove accumulated sediment.
U.S. Pat. No. 6,719,490 to Maestro discloses a stormwater receiving assembly wherein a box-like compartment for accumulating sediment is disposed beneath a plastic dispensing chamber having an arched wall configuration. A top portal is disposed in the apex of the arch directly above the compartment to facilitate joinder to a “riser” access pipe which extends upwardly to a surface access structure such as a manhole at surface ground level. Said riser pipe is generally constructed of rigid polyvinylchloride (PVC) having an inside diameter of 10 inches, which permits passage of a vacuuming tube, generally of 8 inch outside diameter.
Although such sediment-accumulating compartment provides effective results, it is found that because the vacuuming tube must extend further downward a distance of 3-5 feet to reach the sediment, an extra length of the tube must be added onto the customarily employed length of tube. The usual technique for adding a length of tube involves an external coupling device which increases the effective outside diameter of the tube. This, in turn, requires that the riser pipe and top portal must have a larger diameter. However, it has generally been found that enlargement of the top portal diminishes the load-bearing strength of the chamber.
In earlier described installations of the aforesaid underground leaching fields, above ground means are employed for collecting or channeling stormwater which is fed to an underground large diameter manifold pipe system that directs the stormwater to the inlet extremities of the first chambers of each row of chambers. It would be desirable to have greater versatility in the routing of stormwater to the underground leaching field, particularly by making use of conventional street-level grated stormwater receptacles, whose water-collecting capacities are generally rated greater than a conduit of 10 inch diameter.
It is accordingly an object of the present invention to provide a plastic stormwater dispensing chamber of arched configuration capable of receiving a large diameter riser pipe with minimal loss of chamber strength.
It is a further object of this invention to provide an underground stormwater receiving assembly capable of receiving stormwater from street-level grated receptacles.
It is another object of the present invention to provide structural modifications in the chamber to strengthen the chamber to accommodate an enlarged top portal.
These objects and other objects and advantages of the invention will be apparent from the following description.